There are many processes which utilize dry material which is stored in bulk and fed from a bulk container by a screw conveyor, auger, or the like, for batch processing, for example. Recently, large bags have been developed for use in transporting measured quantities of dry material. Generally, in the prior art, this dry material is emptied from the bulk bags into storage bins or feeder bins, and the material is then augered from these feed bins into the process, as desired. Although these bulk bags would otherwise be suitable for rack mounting and direct feeding therefrom, there is an inherent problem with many dry materials that inhibits a bulk bag's use in that manner. Some of these problems include the tendency for the dry material to absorb moisture from the humidity in the air and partially solidify within the bag to thereby impede the free flow of dry material from a pourspout or the like which is often conveniently built into the bottom of bulk bags. This is sometimes referred to as bridging or rat holing. This partial solidification may also be caused merely by the passage of time as the bags are transported or sit awaiting use. Furthermore, a bag may be mounted in a rack and the material adequately loosened to flow freely initially, but the material may then agglomerate or otherwise compact or obstruct the pourspout such that an even, reliable flow of material from the bag until empty is difficult to achieve.
The inventor herein is aware of attempts in the prior art to solve this problem. As best understood, one such prior art attempt consists of a generally rectangular bracket member which is pivotally mounted, much as a child's teeter-totter, and formed in a cradle-like shape. A motor with an eccentric or the like is coupled to an outboard end of the rectangular bracket and used to oscillate the bracket against the bottom of the bag. Because the bag's pourspout has to be loosened and fitted into a surge hopper, the bracket member is initially retracted below the surge hopper and then cranked upwardly into position after the bag is lifted into position above the surge hopper and its pourspout fitted in place. This procedure is necessary to allow unrestricted access to the pourspout for initially loosening it and aligning it with the surge hopper.
While this may improve the flow of material from within the bag, it is not viewed as a complete solution in that the force exerted against the bag is limited to an oscillating teeter-totter motion with a restricted range of movement "into" the bag bottom. Thus, the forced movement of the material in the bag which would have a tendency to break up these agglomerations or partial solidifications is necessarily restricted. Perhaps because of this restricted movement, the prior art teaches the use of a second stage of agitation in the surge hopper, after the dry material has left the bag, to ensure a smooth flow of dry material. In other words, the prior art uses not only the oscillating bracket to agitate the material in the bag, but also a surge hopper with its own agitation mechanism to ensure a reliably loose material suitable for smooth flow such as by augering or the like.
In order to solve these and other problems in the prior art, the inventor herein has succeeded in designing and developing a bracket arrangement as the single agitation mechanism for feeding dry material directly from bags. The bracket is selectively activated whenever flow is called for to physically knead the lower portion of the bag and the dry material adjacent the pourspout which provides a significant improvement in loosening the dry material just before it exits the bag. Additionally, a vibrator may be mounted on the bracket in order to not only deflect the bag bottom but also vibrate it. The inventor's bracket does not just oscillate in a limited range of motion, but it pushes radically upward into the bag as it is pivoted at one end thereof and not in its middle as in the prior art. Also, the control for the bracket assembly can be used to push against the lower portion of the bag once, twice, or repeatedly during the course of material discharge. With different kinds of dry materials, one or more of these different operating routines may be used to best effect.
The bracket assembly essentially consists of a U-shaped bracket which is pivotally mounted beneath the bag at the ends of the legs of the U, and an air cylinder which supports the closed end of the U from the surrounding framework. This U-shaped design and its mounting allow free access to the bag bottom and its pourspout after it has been mounted onto the framework and does not require the crank mechanism for raising the bracket from a lowered position as suggested by the prior art. As the bulk bags in the inventor's system may be arranged in banks, a walkway adjacent one side of the bag and the open end of the U-shaped bracket permits an operator to have free and ready access to the bag bottoms for purposes of unfolding the pourspout where it is secured for storage in shipping purposes, and inserting the pourspout into a downspout or other feed arrangement as is known in the art to provide a ready path for dry material as it exits the bag.
The U-shaped bracket substantially surrounds the pourspout and engages the bottom of the bag which is the portion of the bag closest to the material which immediately exits therefrom and therefore is positioned for maximum effect. The vibrator is positioned on the portion of the U-bracket which engages the bag bottom and is vertically oriented to thereby be maximally coupled to the dry material. The air cylinder is of the rubber bladder inflation type thus permitting the vibrator to be effective by inducing vibrations into the bag through the soft coupling between the U-shaped bracket and the frame. The travel of the U-shaped bracket may be adjusted by physically changing the mounting location of the bracket, and by choosing an air cylinder having a different inflation extension. The U-shape design and movement of the bracket from these positions allow for maximum effectiveness in agitating the dry material while eliminating obstruction of the pourspout.
While the principal advantages and features of the present invention have been briefly described above, a greater understanding of the invention may be attained by referring to the drawings and description of the preferred embodiment which follow.